POSITIVE ELECTRODE ACTIVE MATERIAL, ELECTRODE, AND BATTERY

A positive electrode active material includes olivine lithium manganese iron phosphate, wherein the olivine lithium manganese iron phosphate contains a first dopant at the phosphorus site and a second dopant at the manganese-iron site, and satisfies relationships of ΔG3 < ΔG1 + ΔG2, ΔG2 < 0 kJ/mol, and ΔG3 < 0 kJ/mol where ΔG1 represents free energy of formation produced by substitution of phosphorus at the phosphorus site with the first dopant, ΔG2 represents free energy of formation produced by substitution of iron at the manganese-iron site with the second dopant, and ΔG3 represents free energy of formation produced by substitution of phosphorus at the phosphorus site with the first dopant and substitution of iron at the manganese-iron site with the second dopant.